As a portrait of a personality in flux, Alexis Arquette: She's My Brother (More4) was a masterpiece of expressionistic evasion. Filmed in 2005, this series of wobbly video diaries and disjointed interviews captured the transgender actor (and sibling to Patricia, Rosanna and David) in the months leading up to sex reassignment surgery. Born Robert, Arquette had lived as a female "on and off" since the age of 13, but now felt ready to "take the final step – hah-hah!"

From the footage emerged two distinct Alexises. There was the whooping narcissist who whipped out her fluorescent lime thong at a film premiere. And there was the sensitive, surprisingly prudish philosopher who engaged in endless, gloomy therapy sessions and spoke witheringly of the public's fascination with those who choose to have their "uh-huh" replaced with a "woo-hoo".

Each Alexis promised acres of insight into the difficulties faced by those who find themselves in the wrong body – but She's My Brother never sat still long enough to listen to either of them. One moment we were zooming in on Arquette's engorged pout as she pondered her studied, self-mocking vanity ("Is my ego as big as the universe?"), the next we were crouching in the bushes outside her LA apartment, peering at the closed curtains as we endured another of her increasingly evasive phone calls ("What do you waaaaant from me?").

Perhaps the scrambled format was intended to reflect Arquette's mounting ambivalence towards her operation. More likely is that the producers didn't know their fluorescent lime thong from their elbow.

In the end, we never found out whether Arquette had her uh-huh replaced with a woo-hoo. The last we saw of her (courtesy of a peculiar coda, shot five months later), she was backpedalling testily into the Hollywood sunset, snapping about exploitation, privacy and how her sexuality was "not an open book". Such decisiveness offered a welcome edge of steel to the ambiguity. If only a smidgen of this clarity had been applied by the film's producers.